Method and system for beacon information provisioning, transmissions and protocol enhancements

ABSTRACT

A method for beacon information provisioning, transmissions and protocol enhancements includes defining multiple level beacons based on the attributes of beacon information fields/elements. A short beacon may be used in addition to a primary beacon in space-time block code (STBC) modes, non-STBC modes and in multiple bandwidth modes. The short beacons may also be used for Fast Initial Link Setup (FILS) and to extend system coverage range. Beacon transmissions may use adaptive modulation and coding set/scheme (MCS).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/358,269 filed Mar. 19, 2019, which is a continuation of U.S. patentapplication Ser. No. 13/782,709 filed Mar. 1, 2013, which issued as U.S.Pat. No. 10,237,818 on Mar. 19, 2019, and claims the benefit of U.S.provisional application No. 61/606,180, filed on Mar. 2, 2012; U.S.provisional application No. 61/667,648, filed on Jul. 3, 2012; and U.S.provisional application No. 61/720,750, filed on Oct. 31, 2012, thecontents of which are hereby incorporated by reference herein.

BACKGROUND

A wireless local area network (WLAN) in infrastructure basic service set(BSS) mode has an access point (AP) for the BSS and one or more stations(STAs) associated with the AP. The AP typically has access or interfaceto a distribution system (DS) or another type of wired/wireless networkthat carries traffic in and out of the BSS. Traffic to STAs thatoriginates from outside the BSS arrives through the AP and is deliveredto the STAs. Traffic originating from STAs to destinations outside theBSS is sent to the AP to be delivered to the respective destinations.Traffic between STAs within the BSS (“peer-to-peer” traffic) may also besent through the AP where the source STA sends traffic to the AP and theAP delivers the traffic to the destination STA. A WLAN in IndependentBSS mode has no AP, and STAs communicate directly with each other.

WLAN systems which utilize beacon transmission procedures for discoveryof the AP by the STA, use a periodic transmission of the beacon in theBasic Service Set (BSS) from the AP. The beacon supports variousfunctions in the system by providing an AP Advertisement with the BSSID,Synchronization of the STAs in the BSS, capability information, BSSoperation information, system parameters for medium access, transmitpower limits, as well as many optional information elements. The frameformat for typical beacons for WLAN BSSs may be >100 bytes long and intypical enterprise environment beacons are ˜230 bytes. The overhead ofsuch a beacon may include a substantial amount of information. Forexample, a beacon of 100 bytes at the lowest transmission rate (100Kbps) may require greater than 8 ms transmission time (i.e., at thelowest rate in order for all STAs to be able to decode it). For a beaconinterval of 100 ms, there may be greater than 8% overhead. To support a100 ms fast link setup time, beacon intervals must be significantlyshorter than 100 ms, which would result in an overhead valuesignificantly greater than the 8% overhead estimate.

SUMMARY

Methods and systems for beacon information provisioning, transmissionsand protocol enhancements are described herein. In one method, a singlelarge beacon is split into multiple level beacons for beacon informationprovisioning and transmission based on the attributes of each beaconinformation fields/elements. These attributes may include purpose,usage, periodicity, stability, broadcast/multicast/unicast and the like.Signaling mechanisms and operation procedures may be defined based onthe multiple level beaconing scheme, for both backward compatiblewireless local area network (WLAN) systems and Greenfield WLAN systems.A short beacon may be used in addition to a primary beacon in space-timeblock code (STBC) modes, non-STBC modes and in multiple bandwidth modes.The short beacons may also be used for Fast Initial Link Setup (FILS)and to extend system coverage range. A short beacon with a low ratetransmission and/or with a directional transmission may be used.Modifications to the primary beacon may be made for small bandwidthtransmission to support short beacons and multiple bandwidth modes.Beacon transmissions may use adaptive modulation and coding set/scheme(MCS) sets. Methods to support stopping of processing of packets arealso described.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIGS. 2A and 2B show examples of a single beacon and a multiple levelbeacon scheme, respectively;

FIG. 3 shows an example of multiple level beacon classifications;

FIG. 4 shows an example signalling diagram for a STA and AP during linksetup using multiple level beacons;

FIG. 5 shows an example of a signalling diagram to maintain a WLAN linkin accordance with a multiple level beacon scheme;

FIG. 6 shows example signalling diagram for a traffic indication beacon;

FIG. 7 shows an example short beacon configuration;

FIG. 8 shows an example FILS beacon configuration;

FIG. 9 shows an example method flowchart for a single discovery phaseusing a FILS short beacon;

FIG. 10 shows an example FILS short beacon configuration;

FIG. 11 shows an example method flowchart for STA behaviour usingscanning primitives for FILS short beacon;

FIG. 12 shows an example of a modified primary beacon that includesshort beacon information;

FIG. 13 shows an example modification to a IEEE 802.11ah short beaconframe to carry STBC or non-STBC mode related information;

FIG. 14 shows an example modification to a general short beacon frame tocarry STBC or non-STBC mode related information;

FIG. 15 shows an example of directional short beacon transmission withtwo directions/weights;

FIG. 16 shows an example method flowchart of AP and STA behaviour for apassive scanning method; and

FIG. 17 shows an example of a modified generic PLCP receive procedurewith primitives to support the stopping of processing of packets.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideb and CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. The RAN 104 may be an access service network(ASN) that employs IEEE 802.16 radio technology to communicate with theWTRUs 102 a, 102 b, 102 c over the air interface 116. As will be furtherdiscussed below, the communication links between the differentfunctional entities of the WTRUs 102 a, 102 b, 102 c, the RAN 104, andthe core network 106 may be defined as reference points.

As shown in FIG. 1C, the RAN 104 may include base stations 140 a, 140 b,140 c, and an ASN gateway 142, though it will be appreciated that theRAN 104 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 140 a, 140 b,140 c may each be associated with a particular cell (not shown) in theRAN 104 and may each include one or more transceivers for communicatingwith the WTRUs 102 a, 102 b, 102 c over the air interface 116. In oneembodiment, the base stations 140 a, 140 b, 140 c may implement MIMOtechnology. Thus, the base station 140 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 102 a. The base stations 140 a, 140 b, 140 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 142 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 106, and the like.

The air interface 116 between the WTRUs 102 a, 102 b, 102 c and the RAN104 may be defined as an R1 reference point that implements the IEEE802.16 specification. In addition, each of the WTRUs 102 a, 102 b, 102 cmay establish a logical interface (not shown) with the core network 106.The logical interface between the WTRUs 102 a, 102 b, 102 c and the corenetwork 106 may be defined as an R2 reference point, which may be usedfor authentication, authorization, IP host configuration management,and/or mobility management.

The communication link between each of the base stations 140 a, 140 b,140 c may be defined as an R8 reference point that includes protocolsfor facilitating WTRU handovers and the transfer of data between basestations. The communication link between the base stations 140 a, 140 b,140 c and the ASN gateway 142 may be defined as an R6 reference point.The R6 reference point may include protocols for facilitating mobilitymanagement based on mobility events associated with each of the WTRUs102 a, 102 b, 102 c.

As shown in FIG. 1C, the RAN 104 may be connected to the core network106. The communication link between the RAN 104 and the core network 106may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 106 may include a mobile IP home agent(MIP-HA) 144, an authentication, authorization, accounting (AAA) server146, and a gateway 148. While each of the foregoing elements aredepicted as part of the core network 106, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA may be responsible for IP address management, and may enablethe WTRUs 102 a, 102 b, 102 c to roam between different ASNs and/ordifferent core networks. The MIP-HA 144 may provide the WTRUs 102 a, 102b, 102 c with access to packet-switched networks, such as the Internet110, to facilitate communications between the WTRUs 102 a, 102 b, 102 cand IP-enabled devices. The AAA server 146 may be responsible for userauthentication and for supporting user services. The gateway 148 mayfacilitate interworking with other networks. For example, the gateway148 may provide the WTRUs 102 a, 102 b, 102 c with access tocircuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. In addition, the gateway 148 mayprovide the WTRUs 102 a, 102 b, 102 c with access to the networks 112,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 1C, it will be appreciated that the RAN 104may be connected to other ASNs and the core network 106 may be connectedto other core networks. The communication link between the RAN 104 theother ASNs may be defined as an R4 reference point, which may includeprotocols for coordinating the mobility of the WTRUs 102 a, 102 b, 102 cbetween the RAN 104 and the other ASNs. The communication link betweenthe core network 106 and the other core networks may be defined as an R5reference, which may include protocols for facilitating interworkingbetween home core networks and visited core networks.

Other network 112 may further be connected to an IEEE 802.11 basedwireless local area network (WLAN) 160. The WLAN 160 may include anaccess router 165. The access router may contain gateway functionality.The access router 165 may be in communication with a plurality of accesspoints (APs) 170 a, 170 b. The communication between access router 165and APs 170 a, 170 b may be via wired Ethernet (IEEE 802.3 standards),or any type of wireless communication protocol. AP 170 a is in wirelesscommunication over an air interface with WTRU 102 d.

In a first embodiment, a multiple level beaconing (MLB) scheme isdefined, which organizes beacon information into multiple level beaconsfor beacon information provisioning and transmission. The multiple levelbeacons are defined based on the attributes of each beacon informationfields/elements, e.g., purpose, usage, periodicity, stability,broadcast/multicast/unicast, and the like.

FIGS. 2A and 2B show examples of beacon transmissions. In FIG. 2A, asingle beacon scheme 200 is illustrated, in which each beacon 211 istransmission at a regular beacon interval 212. FIG. 2B shows an exampleof a multiple-level beaconing scheme 210, where four beacon levels aredefined by the beacon's transmission frequency. As shown in FIG. 2B,each beacon level may be transmitted at different periodicities. Level 1represents a fast beacon (e.g., transmitted every 50 ms). Level 2represents a normal beacon transmitted every 100 ms. A long-cycle beaconis transmitted every second for Level 3, and Level 4 represents an eventdriven, non-periodic beacon. The multiple level beacon time intervalsmay be specified as system configuration parameters and managed in IEEE802dot11-MIB, and/or in a lower level beacon (i.e., having shorterintervals), which contains a pointer field pointing to the time of nexttransmission of its next-level beacon.

The contents of the multiple level beacons may be completely different(i.e., no overlapping), partially overlapping (i.e., two differentlevels of beacons may have some common information fields or elements),or forward-inclusive (i.e., where the contents of a lower level beaconare completely included in a next higher level beacon) FIG. 2B shows anexample of forward-inclusive beacons. For example, the Level 4 eventdriven beacon 204 includes all information of the Level 1, Level 2 andLevel 3 beacons. Also note that the Level 1 fast beacon information issent as a single beacon 201, as well as within the Level 2 normal beacon202, Level 3 beacon 203 and Level 4 beacon 204. Similarly, the Level 2beacon information is included in Level 4 and Level 3 beacons 203, 204,in addition to the Level 2 beacon instance 202. The Level 3 beaconinformation is sent both at 203 and at the Level 4 beacon 204.

The organization of beacon information fields and elements in multiplelevel beacons may be based on one or more of the followingconsiderations. The usage or purpose of the beacon informationfields/elements (e.g., for link setup, for transmitting STAidentifications, for PHY parameter descriptions, for trafficindications, for MAC/Network capability indications, and the like) maybe considered. The states of intended reception STAs (e.g.,unauthenticated/unassociated, authenticated/unassociated,authenticated/associated) determined, where different Modulation CodingScheme (MCS) schemes may be used to transmit the different level ofmultiple level beacon frames. The nature of broadcast, multicast, andunicast of the beacon information fields/elements may also beconsidered.

For a beacon information element (IE) (i.e., formatted in Element ID,Length, and information body, in addition to using system configurationparameters to indicate its presence in beacon frames), a new systemconfiguration parameter may also be defined to specify the periodicity,beacon level, and/or delay tolerance of its provisioning. A versionnumber information field, or element, of a beacon may also be includedin the beacon frame for which the information is intended, or forinformation pertaining to lower level beacon frames, or the versionnumbers for all beacons may be included in every beacon, where theversion number represents the change count which increments every timethe contents of the beacon, or beacons, have changed.

The signaling mechanisms, operation, and procedures corresponding to theproposed multiple level beaconing scheme may also defined, for bothbackward compatible WLAN systems and Greenfield WLAN systems.

When applying multiple level beaconing in a Greenfield WLAN system, itmeans all the stations support the multiple level beaconing. In thiscase, the legacy beacon scheme does not need to be supported, where thelegacy beacon scheme refers to that as specified in the current IEEE802.11 standards.

The multiple level beaconing improves the beacon informationprovisioning and transmission efficiency. Instead of minimizing the useof the periodic broadcast transmissions, the AP according to thisembodiment broadcasts and/or sends periodic transmissions only whennecessary. Also, when using periodic transmission, the requiredperiodicity is matched. The following describes an example of themultiple level beaconing, where beacon information fields and elementsare grouped and provisioned based on their usages and purposes.

FIG. 3 shows an example multiple level beacon classification in whichfour levels of beacons are defined according to usages and purposes. Forthe example as shown in FIG. 3, based on the following usageclassification of the beacon information fields and elements, there arefour levels of beacons, one level per class. For simplicity ofdescription, the four levels of beacons are termed Link Setup Beacon(LS-B) 301, Operation Initialization Beacon (OI-B) 302, Link andOperation Maintenance Beacon (LOM-B) 303, and Traffic Indication Beacon(TI-B) 304, respectively.

For the Link Setup Beacon 301, the transmitted beacon informationrelates to (PHY) Link setup for both Rx and Tx for a STA, e.g., TimeStamp, SSID, PHY-specific parameter sets, country, and the like. Withrespect to the Operation Initialization beacon 302, PHY/MAC networkcapability descriptors are sent along with other information needed forOperation initialization (e.g., capability information field andmultiple information IEs (e.g., Supported Rates, Extended SupportedRates, Extended Capabilities, QoS Traffic Capability, HT capability,Interworking, RSN, CF Parameter Set, HT Operation, EDCA Parameter Set,DSE Registered Location, and the like)). The Link and operationmaintenance classification beacon 303 includes information such as a TPCReport, Measurement Pilot Transmission Information, Antenna Information,BSS Average Access Delay, BSS Load, BSS Available Admission Capacity, APChannel Report, Channel Switch Announcement, Quiet, Extended ChannelSwitch Announcement, and the like. The Traffic indication beacon 304includes, for example, TIM, Emergency Alert Identifier, and the like.

The Link Setup Beacon 301 may be broadcasted periodically, where theperiodicity is defined by a system configuration parameter that ismanaged through IEEE 802dot11-MIB. In a WLAN system that requires fastlink setup, the periodicity of the Link Setup Beacon 301 may be set to ashorter interval, e.g., 25 ms or 50 ms, than the current commonly usedbeacon interval (i.e., 100 ms). On the other hand, if the link setup maytolerate some delays, the periodicity of the Link Setup Beacon 301 maybe set to the same as the current commonly used IEEE 802.11 beacon,i.e., 100 ms, or even longer.

The Operation Initialization Beacon 302 may be transmitted in a unicastor broadcast/multicast manner only when the transmitting STA receivesindication that another station or stations are attempting to establishconnectivity. In other words, the transmissions of the OperationInitialization Beacon 302 is not periodical, instead, it isevent-driven. The connection attempt indication may be a receivedrequisition frame for another station, e.g., probe request, associationrequest, or a newly introduced connection request from, or anotification from network element, e.g., a server in the network.

The Link and Operation Maintenance Beacon 303 may be transmitted in aunicast or broadcast/multicast manner either periodically orevent-driven. When periodically, the periodicity may be of longerinterval than the Link Setup Beacon 301. The transmissions of Link andOperation Maintenance Beacon 302 may be triggered by the channelcondition related events, e.g., channel switching, BSS load and/oraccess delay exceed certain thresholds, etc.

The Traffic Indication Beacon 304 may be transmitted in a unicast orbroadcast/multicast manner either periodically or event-driven. If thetransmitting station of the traffic indication beacon knows thelistening windows of the receiving station or stations, it may betransmitted only in such listening windows in unicast manner for asingle station or in multicast manner for a group of stations with thesame listening windows. Otherwise, the Traffic Indication Beacon may betransmitted periodically in a unicast or multicast or broadcast manner,depending on the intended receiving station(s) of the traffic indicationinformation, where the periodicity is chosen based on a trade-offbetween the latency and the overhead of traffic indication delivery. Inaddition, for unicast or multicast beacon transmissions, a higher daterate may be used as compared to the data rate used by broadcasttransmissions, as long as all the intended receiving stations maysupport it.

For each beacon level, a version number or change indicator may be usedin the beacon MAC header or frame body of this level beacon. The changeindicator is a change count which increments every time the contents ofthe beacon, (of this level or next higher level), changes. The systemmay configure a fixed number of beacon contents, each represented by aversion number. The beacon contents of each version may be specified inthe standards or signaled to the STA when being configured.Alternatively, the STA may acquire the version and beacon contentsmapping from receiving each particular version for at least one time.The beacon version number or change indicator may be signaled using thefollowing example methods.

In one example method, the beacon version number or change indicator maybe signaled in the MAC header in the beacon frame reusing the one orseveral information fields which are not used when a beacon istransmitted, (e.g. when Type=“00” and Subtype=“1000”). Examples includeRetry field, More Data field, Order field, Sequence Control field.

In another example, the beacon version number or change indicator may besignaled in the MAC header in the beacon frame using reserved Subtypesfor Management frame type (for example, Type=“00” and Subtype=“0110”,“0111” and “1111” to indicator new beacon level/type).

Alternatively, the beacon version number or change indicator may besignaled in the Physical layer convergence procedure (PLCP) preamble.Different short training field (STF) or long training field (LTF)sequence and/or subcarrier mapping may be used to implicitly indicatedifferent beacon version numbers or the contents of the beacon changes.

In yet another example, the beacon version number or change indicatormay be signaled in the signal (SIG) field in the PLCP header.

For a multiple level beacon system with N levels, a beacon level/typeindicator may be used for the receiving STA to distinguish differentlevels of beacon and their formats. Only ┌log₂ N┐ bits are needed tosignal the beacon level/type. The methods described above may be used tosignal the beacon level/type indicator. If a long information field,(such as the Sequence Control field), in the MAC header is reused forbeacon level/type indicator, then only a fraction of such a informationfield may be actually reused.

With the above multiple level beacon transmissions, a STA may follow aprocedure as shown in FIG. 4 and described below for its link setup andoperation initialization with an AP station in infrastructure BSS modeor another STA in other modes. A first STA, STA-A, starts to searching401 for a WLAN system to connect to, e.g., listening to WLAN signals onWLAN channels. STA-A receives and decodes 402 a Link Setup Beacon 301,from which it obtains the essential information to access the WLANchannel with a STA-B which transmitted the Link Setup Beacon 301. STA-Atransmits 403 a link/operation initialization request to STA-B, whichresponds 404 to STA-A with an Operation Initialization Beacon 302containing the required information to establish an operationalconnection (e.g., security information, the MAC/network capabilityinformation, MAC operation parameters, additional PHY capability (inaddition to the basic PHY link used in Link Setup Beacon 301transmission and link/operation initialization request). STA-A mayrespond 404 to STA-B with its capability information, MAC operationparameters, security information, to continue the link/operationinitialization, until an operational WLAN connection is established 405between STA-A and STA-B, or the attempt of link/operation initializationhas failed, due to some reasons, e.g., security, service provisioning,etc.

Note that, in the above procedure 400 for link setup and operationinitialization, the Link Setup Beacon 301 needs to be broadcastperiodically for a new station to detect an operational WLAN; and theOperation Initialization Beacon 302 is unicast only once upon beingtriggered by the request 403.

FIG. 5 shows an example signaling diagram for a procedure 501 that maybe used to maintain an WLAN link and its operation having beenestablished using the multiple level beacon scheme. STA-B performs linkquality measurements 502 and/or MAC/system performance measurements thatmay be periodically provisioned 501 through unicast ormulticast/broadcast LOM-B 303, at the pre-negotiated or configuredperiodicity. The link operation changes 503 or link operation alertconditions may also trigger 504 the transmissions of LOM-Beacons 303that include, for example, information such as channel switching, BSSload exceeding a predefined threshold, and the like.

For each received beacon of a particular level, the STA-A may obtain thelevel/type of the received beacon from the signaling in the MAC header,PLCP preamble or signal (SIG) field. STA-A may also obtain the versionnumber of the received beacon from the signaling in the MAC header, PLCPpreamble or SIG field. If the beacon contents of the received versionare already known to the STA-A, it may skip reception and decoding ofthe rest of the beacon to save power. The STA-A may also obtain thechange indicator of the received beacon from the signaling in the MACheader, PLCP preamble or SIG field. If the change indicator signals thatthe content of this beacon-level or the next higher level does notchange since its last transmission, it may skip reception and decodingof the rest of the corresponding unchanged beacon to save power. Notethat the above link and operation maintenance procedure 500 is acombination of periodic reporting of link quality/system performancemeasurements 502 and event-driven reporting of link conditionchanges/alerts 503.

FIG. 6 shows an example signaling diagram for a procedure 600 relatingto the traffic indication beacon 304, useful to support power savingoperations. STA-A and STA-C communicate with STA-B configured as an AP.There are two basic types of traffic indication deliveries, depending onwhether or not the transmitting STA of the traffic indication beaconknows the listening windows of the receiving STA or STAs, where thelistening window refers to the time interval during which a power savingmode STA-A is “awake” (i.e., actively listening to the wirelesschannel). At the time a power saving mode is initiated and before thepower saving station actually enters the power saving mode 611, STA-Amay communicate 601 or negotiate its listening window information withanother station STA-B that will deliver its traffic indications. STA-Bbuffers the traffic 612 for STA-A while STA-A sleeps. STA-B (thetransmitting station of the traffic indication beacon 304) transmits 602the traffic indication beacon 304 only in such known listening windows613 in unicast manner for a single station or in multicast manner for agroup of stations with the same listening windows. If STA-B does notknow the listening windows of the intended receiving station STA-C orother receiving STAs, the traffic indication beacon 304 may betransmitted 603 periodically in a unicast or multicast or broadcastmanner, where the periodicity may be defined by a system configurationparameter or parameters managed in IEEE 802dot11-MIB. Prior totransmitting 603 the traffic indication beacon 304, STA-B may buffer 614the traffic 604.

The following description relates to rules for signaling the abovedescribed multiple level beacons. The same management frame may be usedto carry or encode the multiple level beacons, e.g., the current beaconframe or a new category in the action frame or a new management frame byusing a current reserved management frame subtype code point. In the newbeacon frame, a Beacon Type field may be defined and sent to identifythe different levels of beacon frames. The multiple level beacons may beencoded using the different management frames, e.g., using the currentbeacon frame for the Link Setup Beacon 301, using the a currentmanagement frame, e.g., probe response or authentication response orassociation response, to carry the Operation Initialization Beacon 302information, using new categories in the action frame or new managementframes for the other levels of beacon frames. The information for eachlevel of beacon frame may be encoded as information fields orinformation elements, to include optimizations such as, e.g., encode themandatory information in the form of information fields, not informationelements. The system configuration parameters for the multiple levelbeacon scheme may be defined and also introduced into the IEEE802dot11-MIB.

When applying the multiple level beaconing in backward compatible WLANsystems, in addition to supporting multiple level beacon capable STAs,legacy STAs that are not capable of multiple level beacon scheme mayalso be supported. In order to support legacy stations with the existinguser experience of WLAN system performance, the current beacon framesare transmitted with the same information fields and elements at thesame beacon interval as specified by the current IEEE 802.11 standards.In such a WLAN system, the multiple level beacon scheme may still beused to improve the beacon information provisioning and transmissionsfor the stations that are multiple level beacon capable.

In addition, the multiple level beacon scheme may also be used toimprove the system performance for the legacy stations in the followingscenarios. If the Link Setup Beacon 301 still uses the same beacon frameformat as the legacy beacon, but with much less information IEs, thenthe legacy STA may still receive and decode the Link Setup Beacon 301,as the IE structure allows flexible inclusions of IEs due to the use ofthe Element ID and Length fields. In this way, the legacy STA duringlink setup may get the SSID and essential PHY link parameters from theLink Setup Beacons 301. Its link setup may be speeded up due to morefrequent transmissions of the Link Setup Beacon 301, particularly, whenthe passive scanning has to be used, e.g., for regulatory reasons. Afterreceiving and decoding a Link Setup Beacon 301, if the STA still needsmore information about the AP, it may send a request message, e.g.,Probe Request frame, to the AP. The traffic indication map (TIM)elements for the multiple level bacon capable stations are no longerincluded in the legacy beacons, so that the size of the legacy beaconwill be reduced, as compared to a beacon containing a TIM for all theassociated stations. Since the new Traffic Indication Beacon 304 may betransmitted in a multicast/unicast manner and also potentially in higherMCSs, the overall TIM transmission efficiency for all associated STAsmay be improved.

The above methods related to multiple level beaconing offer improvedutilization of system resources unlike a single beacon scheme in whichthe system description/configuration information is confined to a singlebeacon. Unlike a single beacon scheme, where the various informationfields and information elements would be lumped together for delivery ona same transmission interval, the multiple level beaconing schemereduces system overhead and is capable of efficiently provisioning anddelivering a variety of information, e.g., usage, static/dynamic nature,and intended reception STA status, etc. to the STAs in the network.

In a second embodiment, a short beacon for transmission in multiplebandwidth systems is defined. A short beacon may carry only theessential information in order to reduce medium occupancy and powerconsumptions for transmission (TX) at AP and reception (RX) at STAs,compared to a normal standard beacon (also referred to herein as “long”beacon). For similar overhead as a long beacon, the short beacon mayallow for shorter beacon intervals for better synchronization and powersaving (e.g., by allowing STAs to sleep more). The short beacon may alsoperform primary beacon function, such as for example, announcing the AP,synchronizing the STAs, disclosing minimum set of information for TX inthe BSS, and providing indication of Power Save (TIM). The short beaconmay be defined to be <20 bytes.

AP/STA behavior with respect to short beacons may include the APbroadcasting regular beacons at a Beacon Interval and short beaconsbetween the regular beacons. The STAs may acquire basic informationabout the AP through the short beacon, and only acquired at associationby listening to full beacon or with a probe request. Once a STA isassociated with the AP, it may listen to short beacons forsynchronization. The AP may indicate change of information by adding a“change sequence” to the short beacon to force STAs to listen for a fullbeacon or through probe request.

FIG. 7 illustrates contents for a short beacon 700, including a FrameControl field 701. An example of a Short Beacon indication in the FrameControl field 701 is a type/subtype field value of [B3 B2]=[11], [B7 B6B5 B4]=[0 0 0 1]. A Source Address (SA) 702 may be included as MACAddress of the AP. A Compressed SSID 703 may contain a representation ofthe SSID of the network that allows a device that already knows thenetwork to discover it and may for example be a standardized hash offull SSID. A Timestamp 704 that may be 4 byte least significant bits(LSBs) of the Timestamp at the AP. The 4 bytes may be sufficient to keepup synchronization for a device that is already associated with the APand has received the full AP Timestamp once. A sensor node may maintaintime sync with its AP if it checks a Short Beacon as rarely as once aday. The short beacon also includes a Change Sequence field 705 shown as1 byte long and in which a counter is incremented if full beaconinformation changes.

An Info Field 706 of the short beacon 700 may carry information for anew device trying to associate, including, but not limited to thefollowing. A Bandwidth field 761 of 4 bits, where for example, a value0000 indicates 1 MHz BSSS and all other values represent a bandwidththat is twice the value indicated by the Bandwidth field. A Privacyfield 762 of 1 bit to indicate if the network supports privacy.Additional bits 763 may be reserved for future functionality. The shortbeacon 700 also includes a Duration to Next Beacon field 707, optionalIEs 708 and CRC field 709.

The WLAN in this embodiment may support more than one bandwidth mode.One such example is in the sub-1 GHz spectrum where there may be BSSsupport that allows operation of 2 MHz and 1 MHz bandwidth modes. Whiledescribed with reference to 1 MHz and 2 MHz bands as an example, thisembodiment may apply to other bandwidth combinations as well.

The following rules for short beacon transmission in various bandwidthmodes may be used. In scenarios where only 1 MHz bandwidth transmissionis supported, (e.g., because of spectrum allocation and regulations),the AP may transmit only 1 MHz primary beacon and 1 MHz mode shortbeacon. In scenarios where only 2 MHz bandwidth transmission issupported, (e.g., because of spectrum allocation and regulations), theAP may transmit only 2 MHz Primary Beacon and 2 MHz mode Short Beacon.In scenarios where 2 MHz bandwidth transmission is supported and 1 MHzbandwidth transmission is supported as well, (e.g., because of spectrumallocation and regulations), the AP (or STA in IBSS mode) may transmit:(a) a 2 MHz Primary Beacon and also a 2 MHz mode Short Beacon; or (b) a1 MHz Primary Beacon and also a 1 MHz mode Short Beacon. In addition,depending on regulations, the 1 MHz primary beacon and 1 MHz mode shortbeacon may be transmitted: (a) in the upper 1 MHz of a 2 MHz band; or(b) in the lower 1 MHz of a 2 MHz band.

Note that a short beacon may be transmitted in any combination with thevarious bandwidth modes. Some examples of such combinations are: (1)non-STBC 1 MHz bandwidth mode; (2) STBC 1 MHz bandwidth mode; (3)non-STBC 2 MHz bandwidth mode; or (4) STBC 2 MHz bandwidth mode. The 1MHz short beacon may be transmitted at a known time offset from: (1) the1 MHz primary beacon; (2) the 2 MHz primary beacon; or (3) the 2 MHzshort beacon.

An AP, (or STA in IBSS mode), may use a basic MCS (modulation and codingset) from a basic MCS set that is specified in the system to transmit anon-STBC beacon frame. Such a basic MCS set may be advertized by theprimary beacon.

The above described methods related to the short beacons enable WLANsystems based on new PHY, and MAC, extensions targeted for smallerbandwidth transmissions to support more than one bandwidth mode withcorresponding short beacons to support transmission in each bandwidthmode.

In a third embodiment, a short beacon for fast initial link setup (FILS)may provide information to speed up each of the link setup phases. AFILS beacon, which is another form of short beacon to speed up APdiscovery, may carry necessary information for AP discovery. The FILSbeacon may be utilized during a WLAN link setup process. Since beaconsare part of the primary tools to provide information about the AP to theSTAs at the very beginning of the initial link setup process, beaconsmay include information that may facilitate a speedy link setup in orderto satisfy functional requirements. The FILS process may include thefollowing five phases: 1) AP Discovery; 2) Network Discovery; 3)Additional time synchronization function (TSF); 4) Authentication andAssociation; and 5) Higher Layer IP Setup. The FILS beacon may advertisethe AP and may contain several necessary elements for discovery. TheFILS beacon does not replace the traditional beacon frame, but rather isto be sent much more frequently between traditional beacons.

FIG. 8 shows an example configuration for a FILS beacon 800 thatincludes an SSID field 801, and an optional Network Identifier 802. Thetransmit pattern of the FILS beacon may be a predefined set of transmitmodes, and where one mode is randomly chosen, for example, evenly setsix time points within a beacon period. Another pattern may be based onsetting a time length T, where AP may send out a FILS beacon if it doesnot receive any of beacon, Probe Response or FILS beacon for T. Apattern may be periodically transmitted at a frequency higher thanbeacon. If transmit time is overlapped with beacon, only beacon may betransmitted.

An enhanced FILS beacon is defined that speeds up the link setupprocess. The methods are also applicable to other WiFi systems thattransmit frames carrying a subset of the information in the full beacon,for example IEEE 802.11ah. A description is provided herein forinformation that may be included for each of the link setup steps below.For FILS purpose, the information included in the following section thatcan speed up each of the link setup phases may be used alone and withoutother information or may be used in any combination or subset of theremainder of the information. The terms FILS beacon, FILS short beaconand FILS discovery frames may be used interchangeably.

The phases of AP Discovery and Network Discovery in the FILS process maybe combined into one single phase since the ultimate purpose is for STAsto discover APs with appropriate network services.

FIG. 9 shows an example method flowchart 900 for combining a singleAP/BSS and network discovery phase with a FILS short beacon. Whilescanning, a non-AP STA receives 901 a FILS short beacon frame. The STAdetermines 902 whether the AP/BSS is the right candidate to associatewith. If not, the STA continues scanning 906. If the AP/BSS isappropriate, then the STA determines 903 whether the FILS short beaconcontains the information of the access network. If not, then the STAobtains 907 the information of the access network using, for example,the General Advertisement service/Access Network Query Protocol(GAS/ANAP). However, if at 903, the STA detects the information in theFILS shot beacon, then the STA checks 904 whether the access network isthe correct candidate to connect to. If so, then the STA proceeds 905 tothe next step of FILS process without having to obtain the accessnetwork information via regular mechanisms, such as GAS/ANQP. However,if the STA determines that the access network is not the appropriatecandidate, then the STA continues the scanning process 906.

FIG. 10 shows a FILS short beacon that may include, besides the basicinformation on the BSS that a STA would require to be associated withthe AP, (such as supported rate, beacon interval, etc.), Interworking1001, Advertisement Protocol 1002 and Roaming Consortium 1003Information Elements (IE). In addition, information on the networkservices may be included in the FILS short beacon. For example, the FILSshort beacon may include the network type information, (private, publicand the like), IP address availability 1004, operator's domain name1005, Network Access Identifier (NM) Realm List 1006, 3GPP CellularNetwork information 1007, and the like, so that the STA may skip theAdvertisement Protocol packet exchanges over GAS and directly proceed tothe next phase of FILS.

The FILS short beacon from an AP may also include a list of APs 1008 (orBSS's) that have similar network services as the transmitting AP. Forexample, the FILS short beacon from an AP of a particular provider mayinclude a list of APs from the same provider in the immediate area. Inthis way, passive or active scanning to these APs may be skipped bynewly arriving STAs which may significantly reduce the initial linksetup time.

The FILS short beacon may also include, besides providing a Timestamp1009 or for example, 32 LSB of the Timestamp, along with basicinformation of the BSS network service the AP provides. Once a STAidentifies the appropriate AP with the appropriate network service, itmay adapt the TSF from the FILS short beacon to perform the TSF. Oneround of packet exchanges may be skipped and the STA may directlyproceed to the next step of Authentication and Association.

Alternatively, the FILS short beacon may not include all networkservices related information, but it includes some key information toallow the STA to quickly screen out undesired AP/BSS in terms of networkservices characteristics and reduces the candidate network that the STAneeds to perform QAS query in the network discovery phase. By receivingthe FILS short beacon, the STA may screen out undesired AP/BSS bychecking network services related information in the FILS beacon. Forexample, a STA that uses an IPV6 address finds out the “Address type notavailable” for IPV6 in the FILS beacon received from a particular AP,then it may not perform the QAS query to the network of this AP.

The FILS short beacon or discovery frame may include information onauthentication, for example, as a part of the NAI Realm List, such asacceptable credential types and EAP methods. Alternatively, a FILSdiscovery frame may include such information in the NetworkAuthentication Type information.

The FILS short beacon may also include information on Higher Layer IPSetup, such as IP Address Type Availability information 1010.

The address 3 field in the MAC header of the FILS discovery frame may beomitted. The recipient may still obtain the BSSID (MAC address) from thesource address (SA) field in the MAC header of the FILS discovery frame.

The following scan primitives are defined with respect to MAC layermanagement entity (MLME) for implementing the FILS short beacon. TheMLME-SCAN.confirm primitive may be immediately invoked to report onevery found BSS during the scan procedure. Table 1 shows a first fieldthat may be contained in the MLME-SCAN.confirm primitive.

TABLE 1 Name Type Valid Range Description BSSDescription Set of BSS N/AThe BSSDescriptionFromFILS- FromFILS- DescriptionFrom- DiscoveryFrameSetis returned to Discovery- FILSDiscovery- indicate the results of thescan FrameSet Frame request derived from FILS Discovery Frame. It is aset containing zero or more instances of a BSSDescriptionFromFILS-DiscoveryFrame. Present only if the value of dot11FILSActivated is true.Each BSSDescriptionFromFILSDiscoveryFrame may consist of the elementsshown in Table 2.

TABLE 2 Name Type Valid Range Description Compressed Octet string 0-4octets The hashed SSID of the found BSS SSID Short Integer N/A The 4byte LSBs of the Timestamp timestamp of the received frame (proberesponse/beacon) from the found BSS Time to the next Integer N/A Thetime between the received FILS full beacon discovery frame to the nextfull beacon MAC Address MAC address 6 bytes MAC Address of the AP isobtained of the AP from the Source address (SA) in the received FILSdiscovery frame FILS Discovery Integer N/A basic periodicity of FILS(FD) Interval Discovery frames, in units of TUs (i.e., 1024us) CondensedAs defined in IEEE N/A uses the same 2-byte condensed Country Std802.11 ™-2012: country string as in MP frame; string Wireless LAN Mediumalthough 3 bytes in Access Control (MAC) dot11CountryString and PhysicalLayer (PHY) Specifications Operation As defined in IEEE N/A indicatesthe operating class value class Std 802.11 ™-2012: for the operatingchannel, as Wireless LAN Medium defined in Annex E. Access Control (MAC)and Physical Layer (PHY) Specifications Operation As defined in IEEE N/Aindicates the operating channel, channel Std 802.11 ™-2012: as definedin Annex E. Wireless LAN Medium Access Control (MAC) and Physical Layer(PHY) Specifications Power As defined in IEEE N/A the informationnecessary to allow a constraints Std 802.11 ™-2012: STA to determine thelocal maximum Wireless LAN Medium transmit power in the current channel.Access Control (MAC) and Physical Layer (PHY) Specifications Access Asdefined in IEEE 4 bits The type of access network (such as network typeStd 802.11 ™-2012: public, private and etc.) (optional) Wireless LANMedium Access Control (MAC) and Physical Layer (PHY) SpecificationsCondensed As defined in IEEE N/A Authentication methods and types of NAIRealm Std 802.11u ™-2011 acceptable credentials List or NetworkAuthentication Type information (optional) Condensed As defined in IEEEN/A Identifying the roaming consortium Roaming Std 802.11u ™-2011 and/orSSP whose security credentials consortium can be used to authenticate(optional) IP address As defined in IEEE N/A Availability of IP addressof various availability or Std 802.11u ™-2011 types of the found BSScondensed IP address availability (optional)

For the MLME-Scan.request primitive, two new parametersMaxChannelTimefor-FILSDiscoveryFrame andMinChannelTimeforFILSDiscovery-Frame in the MLME-Scan.request primitivemay be added. These are shown in Table 3.

TABLE 3 Name Type Valid Range Description MaxChannelTime- Integer≤MaxChannel-Time The maximum time (in TU) forFILSDiscovery- to spend oneach channel Frame when scanning for FILS discovery frame, and isoptionally present if the dot11FILSActivated is true. MinChannelTime-Integer ≤MaxChannel-Time The minimum time (in TU) forFILSDiscovery- tospend on each channel Frame when scanning for FILS discovery frame. Thismay be optionally present if the dot11FILSActivated is true.

Alternatively, the immediate invoke of MLME-Scan.confirm to report onevery found BSS during the scan procedure may be configured/requested byadding a new parameter/field called ReportOption in theMLME-Scan.request primitive, as shown in Table 4.

TABLE 4 Name Type Valid Range Description ReportOption EnumerationRegular_Report, Indicates the option to report Immediate_Report (passiveor active) scan results. If Regular_Report, it indicates the STA mayfollow the same procedure to report scan results as in currentstandards. IEEE Std 802.11 ™- 2012: Wireless LAN Medium Access Control(MAC) and Physical Layer (PHY) Specifications If Immediate_Report, itindicates the STA may immediately invoke an MLME-Scan.confirm primitiveto report on every found BSS during the scan procedure.

The scanning STA may report the found BSS/AP according to theReportOption parameter in the corresponding MLME-Scan.request primitive.

A FILS short beacon may be implemented according to the following. TheFILS short beacon may be implemented with the same management frame or anew management frame or action frame. The FILS short beacon may beimplemented as a broadcast/unicast frame. The additional informationincluded in the FILS short beacon may be implemented as existing IEssuch as Interworking, Advertisement Protocol and Roaming Consortium IEs,or one or more new IE(s) containing all or a subset of information oninternetworking, advertisement protocol, roaming consortium, operator'sdomain name, NM Realm List, 3GPP Cellular Network information,Timestamp, IP Address Type Availability, Network Authentication Typeinformation or other information related to AP Discovery, NetworkDiscovery, Additional TSF, Authentication and Association and HigherLayer IP Setup.

A FILS enabled AP may transmit FILS short beacons, which contain eitherall or a subset of the information that may facilitate fast initial linksetup for one or more phases, in addition to the basic BSS informationsuch as supported data rates, beacon interval, and the like. A STA thatperforms passive scanning may use a hashing function to obtain thecompressed service set ID (SSID) from the full SSID to calculate thehashed SSID from SSID or SSIDList parameter in the MLME-SCAN.requestprimitive and to compare it with the received compressed SSID.

To become a member of a particular extended service set (ESS) usingpassive scanning, a STA may scan for beacon frames containing that ESS'sSSID, returning all beacon frames matching the desired SSID in theBSSDescriptionSet parameter of the corresponding MLME-SCAN.confirmprimitive with the appropriate bits in the Capabilities Informationfield indicating whether the beacon frame came from an infrastructureBSS or independent BSS (IBSS).

If the value of dot11FILSActivated is true, the STA may additionallyscan for FILS Discovery frames, returning all Discovery frames matchingthe desired parameters, (such as SSID and the like), in thecorresponding MLME-SCAN.request primitive usingBSSDescriptionFromFILSDiscoveryFrameSet in the MLME-SCAN.confirmprimitive. For example, a Discovery frame may be considered to bematched with the desired parameters in the correspondingMLME-SCAN.request primitive when the compressed SSID of received FILSDiscovery frames matches the hashed SSID or SSIDList parameter (if theyare specified in the corresponding MLME-SCAN.request primitive).

The STA may listen to each channel scanned for no longer than a maximumduration defined by the MaxChannelTime parameter. Alternatively, a STAmay listen to each channel scanned for no longer than a maximum durationdefined by the MaxChannelTime_FILS parameter, (as defined herein). Inaddition a STA may listen to each channel scanned for no less than aminimum duration defined by the MinChannelTime_FILS parameter (asdefined herein).

FIG. 11 shows a method flowchart for an example procedure that the FILSenabled STA may follow. The FILS enabled STA may skip orsimplify/optimize certain FILS phases according to the informationavailable in the FILS information contained in the FILS short beacon.

The following MLME primitives are processed by the STA's MAC sublayerand MLME. Upon receipt of the MLME-SCAN.request primitive 1101 withScanType indicating passive scan, a STA may perform passive scanning oneach channel included in the ChannelList parameter in theMLME-SCAN.request primitive. The FILS enabled STA scans the channel 1102for beacons/FILS Discovery frames if at least one PHY-CCA.indication(busy) primitive has been detected before the ProbeTimer reachesMinChannelTimeforFlLSDiscoveryFrame, and until the MaxChannelTimeforFILSDiscoveryFrame elapses. If a FILS enabled STA receives a FILS beacon(or Discovery frame) 1103 from an AP, then the following may apply.

A MLME-SCAN.confirm primitive may be invoked and reported 1104 for everyBSS found using BSSDescriptionFrom_FILSDiscoveryFrameSet depending onthe parameters such as SSID, SSIDList and/or access network type in theMLME-SCAN.request primitive. A MLME-SCAN.confirm primitive may beinvoked and reported 1104 for every BSS found if a wildcard SSID and awildcard access network type are used in MLME-SCAN.request primitive. Ifthe MLME-SCAN.request primitive specifies a SSID or a SSID List, thenthe STA may compute the hash of the SSID or SSIDs in the SSID list andcompare with the received compressed SSID. If not matched, the STA maychoose not to invoke a MLME-SCAN.confirm primitive. If matched, aMLME-SCAN.confirm primitive is invoked and reported 1104. If theMLME-SCAN.request primitive specifies a BSSID, then the STA may comparethe requested BSSID with the SA field of the received FILS Discoveryframe. If not matched, the STA may choose not to invoke aMLME-SCAN.confirm primitive. If matched, a MLME-SCAN.confirm primitiveis invoked and reported 1104. If the MLME-SCAN.request primitivespecifies a particular access network type, then the STA may compare thereceived network access type field in the received FILS discovery framewith the access network type in the MLME-SCAN.request primitive. If notmatched, the STA may choose not to invoke a MLME-SCAN.confirm primitive.If matched, a MLME-SCAN.confirm primitive is invoked and reported 1104.

The FILS enabled STA, (or the station management entity (SME) within theSTA), may evaluate the received MLME-SCAN.confirm primitive, (or thereceived FILS beacon), and determine whether the basic BSS requirementsin the FILS beacon may be supported by itself and whether there issufficient network service information 1105. If there is no or notsufficient network service information and the basic BSS requirementscan be supported, then more information may be requested/acquired 1107through Advertisement Protocol packet exchanges over GAS as indicated bythe FILS.

If there is sufficient network service information and the basic BSSrequirements can be supported, however, the provided network servicedoes not satisfy the STA's requirements 1106, then the STA may notperform network discovery or association with the found AP, and maycontinue to scan 1108 for other suitable APs. The STA may consider thatthe provided network service does not satisfy the STA's requirements ifone or any combination of the following example conditions are met: (1)the SSP whose networks are accessible via the AP or the roamingconsortium, (group of SSPs with inter-SSP roaming agreement), is not thepreferred network/operator/supplier of the STA; (2) the IP address typethat the STA supports is not available, (for example, IPv4 address notavailable and the STA is a IPV4 only STA); or (3) authentication methodsand acceptable credentials are not the preferred ones of the STA.Additionally, if the FILS beacon contains information on more APs whichprovides similar network service, the STA may not perform networkdiscovery or association with these listed APs and continue to scan forother suitable APs.

If there is sufficient network service information and the basic BSSrequirements can be supported, and the provided network services matchthe requirement of the STA, the STA may decide to select this AP toassociate with, and skip the network services discovery 1112 and proceedto TSF 1113, described below.

After evaluating the received MLME-SCAN.confirm primitive, the STA, (orthe SME within the STA), may decide to stop entire passive scanning onall channels or continue to scan for other suitable APs. If the SMEdecides to stop the ongoing passive scanning, it may proceed to step1111. If the SME decides to continue the ongoing passive scanning, itmay proceed to 1109.

The STA, (or the SME within the STA), may generate a MLME-SCAN.stopprimitive 1111, with the field of ScanStopType being set to “Stop_All”.Upon receiving the MLME-Scan-STOP.request primitive, the STA (via theMLME) may cancel passive scanning on this channel and may generate anMLME-SCAN.confirm primitive with theBSSDescription-FromFILSDiscoveryFrameSet containing all of the receivedinformation of the channels/BSSs. Then the STA may proceed to networkservices discovery 1112, or directly to TSF 1113.

The STA may continue to search for FILS discovery frames on the currentchannel until the MaxChannelTimeforFlLSDiscoveryFrame elapses 1109. Whenthe scan time reaches MaxChannelTimeforFlLSDiscoveryFrame, the STA maystop scanning of the channel, may generate an MLME-SCAN.confirmprimitive to report scan results, and repeat the above scanning processon the next channel 1110.

The network services information in the above may be obtained from thereceived FILS Discovery frames, (broadcast) Probe Response frames orother management frames.

The STA may perform network services discovery (GAS query) with theselected AP(s) 1112. If some (but not all) network services informationhas been received in previous steps, the STA may optimize the GAS querywith the network by: (a) skipping APs that has network services that theSTA cannot not use/support or does not prefer; (b) not performing GASquery of network services information that are already acquired fromFILS discovery frames in previous steps. The STA may conduct timingsynchronization function (TSF) 1113 using the Timestamp contained in theFILS beacon. The STA may conduct Authentication/Association 1114 usingthe information contained in the FILS beacon onauthentication/association. If parallel or concurrent operation ofauthentication/association and Higher Layer IP Setup is supported, thenHigher Layer IP Setup procedures performed concurrently may use the IPAddress Type Availability information acquired from FILS discoveryframes in previous steps. For example, if IPv4 address is not availablebut IPv6 address is available, then the concurrent Higher Layer IP Setupprocedures may use IPv6 address type (e.g., IPv6 address type isrequested in the IP-CFG-REQ message).

The STA may conduct Higher Layer IP Setup 1115 using the IP Address TypeAvailability information acquired from FILS discovery frames in previoussteps.

According to the above described methods related to the FILS beacon, theFILS short beacon, and FILS discovery frames, WLAN systems are enabledto support faster link setup for STAs, (e.g. less than 100 ms), and tosupport a much larger number of STAs than conventional FILS schemes asthe STAs enter the BSS at the same time. The above embodiment related toFILS may enable a WLAN to support more than 100 STAs, and also mayprovide fast link setup within 1 second.

According to the following embodiment, a primary beacon may be modifiedto support a short beacon feature. Specifically the primary beacon needsto carry short beacon related information. An example illustration ofsuch a modified primary beacon 1200 is shown is FIG. 12. STAs receivingthe modified primary beacon 1200 may read the short beacon relatedinformation field(s) 1201 in the modified primary beacon 1200 todetermine how to receive the short beacon. Such information may includeone or more of an indication of transmission or presence of a shortbeacon 1202, a short beacon transmission time information 1203 (e.g., inthe form of absolute time, time offset from the primary beacon etc),periodicity of the short beacon (how frequently it is transmitted) 1204,an indication of transmission or presence of STBC mode and non-STBCmodes of the short beacon 1205, an indication of transmission orpresence of short beacon in bandwidth mode 1 MHz 1206, and an indicationof transmission or presence of a short beacon in bandwidth mode 2 MHz1207. While bandwidth modes for 1 MHz and 2 MHz are shown in thisexample, other bandwidth mode values may be alternatively implemented.

The short beacon related information may be included in any part of theprimary beacon frame. In one embodiment it may be included in a newlycreated short beacon information element to be carried in the primarybeacon. The short beacon related information may be included as part ofan Operation element of the primary beacon where the Operation elementis used by the AP to control the operation of STAs in the BSS. In thiscase the STAs receive the short beacon information by interpreting theOperation element in the received primary beacon. The primary beacon maybe transmitted by an AP, (or STA in IBSS mode), in non-STBC mode andalso in an STBC mode.

In another embodiment, multiple bandwidth modes may be supported by aWLAN with respect to a primary beacon. One such example is in the sub-1GHz spectrum where there may be BSS support that allows operation of 2MHz and 1 MHz bandwidth modes. While the embodiments described hereinare with respect to 1 MHz and 2 MHz, they apply to other bandwidthcombinations as well.

In systems where more than one bandwidth is supported, there may be aprimary beacon transmitted corresponding to each of the bandwidth modes.For example, the primary beacon may be transmitted in either a 2 MHzbandwidth mode or a 1 MHz bandwidth mode in systems operating in thesub-1 GHz frequency band. The primary beacon in each bandwidth modewould include beacon information that is specific to that bandwidth modeto support transmission in that bandwidth mode. The primary beacon maybe transmitted with signaling of associated bandwidth mode information.This associated bandwidth mode information may be included in PHYportion of the primary beacon and may also be included in the MACportion of the primary beacon.

In the PHY portion of primary beacon the associated bandwidth modeinformation may be, for example, in the Signal field of the PHY preambleand may, for example, include bandwidth indication with other bandwidthmode information to decode bandwidth transmission format. For example,such information may be signaled explicitly using a specificbit(s)/field. When a primary beacon is transmitted, a STA decodes thepreamble signal field in the PHY header to obtain the bandwidth modeinformation. In another embodiment, the associated bandwidth modeinformation may be signaled implicitly by the specific type of trainingfield(s) used in the PHY preamble. In this case, a STA receiving theprimary beacon may obtain the bandwidth mode indication by processingthe training field(s). If the bandwidth mode information, (obtained byprocessing the preamble signal field or training fields), indicates thatthe primary beacon frame is of a specific bandwidth mode then: (1) a STAnot capable of receiving that bandwidth mode ignores the rest of theprimary beacon frame; and/or (2) a STA capable of receiving thatbandwidth mode proceeds to decodes the frame to receive the full frameof the primary beacon.

In the MAC portion of the primary beacon the associated bandwidth modeinformation may be for example in the frame body of the primary beaconand may for example indicate one or more of: (1) the primary beaconcarrying this indication is of a specific bandwidth mode (e.g., either a1 MHz or 2 MHz); (2) the bandwidth modes in which the primary beacon istransmitted/supported, (e.g., 1 MHz and 2 MHz modes). An STA thatdecodes the MAC portion of the primary beacon: (1) on seeing anindication that it is of a specific bandwidth mode, (e.g., either a 1MHz or 2 MHz), may treat the contents of the primary beacon asassociated with that bandwidth mode; and/or (2) on seeing the bandwidthmodes being transmitted/supported may be aware of the various bandwidthmodes of the primary beacon being transmitted/supported.

The 1 MHz primary beacon may be transmitted at a known time offset fromthe 2 MHz primary beacon when both bandwidth modes are in operation.Based on regulatory needs, the 1 MHz primary beacon and 1 MHz mode shortbeacon may be transmitted: (1) in the upper 1 MHz of a 2 MHz band;and/or (2) in the lower 1 MHz of a 2 MHz band.

According to the above described embodiment related to primary beaconsupport for short beacon, WLAN systems that are based on new PHY, andMAC, extensions targeted for smaller bandwidth transmissions may alsosupport more than one bandwidth mode with corresponding primary beaconsto support transmission in each bandwidth mode.

In another embodiment, short beacons may support various modes oftransmission. Some WLAN systems may support more than one mode oftransmission, such as STBC or non-STBC modes. STAs operating in variousmodes may need support from the AP in the form of short beacons invarious modes to operate efficiently in the BSS. The short beacon may bemodified to support various modes, (e.g., STBC and non-STBC), and carrymode related information.

The short beacon may be transmitted in a non-STBC mode and a STBC modewhen both non-STBC and STBC modes are supported in the system. The shortbeacon may also carry an indication of whether it is being transmittedin a STBC mode or non-STBC mode. This STBC mode indication may beincluded in PHY preamble of the short beacon, and may also be includedin the MAC portion of the short beacon for example in the frame body ofthe short beacon as part of short beacon specific information.

In the PHY portion of the short beacon, the associated STBC informationmay be for example in the Signal field of the PHY preamble and may forexample include STBC indication with additional information to decodethe STBC modulation. When a STBC short beacon is transmitted, a STAdecodes the preamble signal field in the PHY header. If the preamblesignal field indicates that it is an STBC frame then: (1) a non-STBCSTA, (not capable of receiving STBC frames), ignores the rest of theframe; and/or (2) an STBC STA (capable of receiving STBC frames),interprets and decodes the frame to obtain the STBC short beacon.

In the MAC portion of the short beacon, the associated STBC informationmay be for example in the frame body of the short beacon and may forexample indicate one or more of: (1) the short beacon carrying thisindication is an STBC or a non-STBC short beacon; and/or (2) both STBCand non-STBC modes short beacon are transmitted/supported. A STA thatdecodes the MAC portion of the Short beacon: (1) on seeing an indicationthat it is an STBC or non-STBC short beacon may treat the contents ofthe short beacon as that of an STBC or non-STBC short beacon,respectively; and/or (2) on seeing the indication of whether both STBCand non-STBC modes of the short beacon are transmitted/supported may beaware of that information.

The STBC mode of operation for the short beacon may also be implicitlyassociated with the bandwidth of operation. For example, if a 1 MHz onlybandwidth mode of operation is used only a non-STBC mode of operationmay be used for the short beacon.

In FIG. 13, an example of a modified short beacon frame 1300 is shownhaving STBC or non-STBC mode related information contained in the framebody. This information may be included anywhere in the frame body, suchas in the Info field 1301, the Short Beacon Specific Info field 1302 (asshown), a new field, and/or in any of other field of the frame body.

In FIG. 14, an example of a short beacon frame 1400 is shown having STBCor non-STBC mode related information contained in the short beacon field1401. However, this STBC mode information may be included anywhere inthe frame body of the short beacon frame 1400.

An AP, (or STA in IBSS mode), may use a basic STBC MCS from a basic STBCMCS set that is specified in the system to transmit an STBC beaconframe. The STBC short beacon may be transmitted at a known or advertizedtime (e.g., advertized by the primary beacon), such as for example at anoffset from non-STBC short beacon, at an offset from the non-STBCprimary beacon; and/or at an offset from the STBC primary beacon.

According to the above described embodiment related to primary beaconbandwidth modes, WLAN systems based on new PHY, and MAC, extensionstargeted for smaller bandwidth transmissions are enabled to also supportmore than one mode of transmission, for example non-STBC and STBC modes.Specifically STAs in both non-STBC and STBC modes may be supported bythe BSS. In contrast, systems relying only on a primary beacon in STBCmode to provide beacon information in the BSS would result in highsystem overhead.

In another embodiment, an appropriate MCS, (higher than the lowestsupported MCS), may be chosen and used for a beacon transmission withoutcompromising the purpose of that beacon. In this way, it may providereduced medium occupation time in each beacon interval, increase mediumaccess efficiency and provide power saving for both the transmitting APsand the receiving STAs.

The short beacon used to indicate the presence of the AP and the BSS maybe transmitted using the lowest MCS contained in the support rates set.In order to provide information for all potential STAs that mayassociate with the AP, the short beacon may be transmitted with the mostrobust data rate.

Short beacons for the STAs that are already associated with the AP donot have to be transmitted using the lowest and most robust MCS sincethe AP already has information on these STAs. The MCS used forassociated STAs may depend on which group the short beacon is meant for.The MCS selection criteria for an AP to transmit beacons may include thecriteria described in the following sections.

The STAs in the BSS may be grouped based on their RSSI level recorded atthe AP. For example, in a BSS where there are a large number of STAs,the STAs may be divided into groups and some of the groups are put intosleep while the other groups are awake to listen for beacons or totransmit and receive packets. If the groups are divided into groups bybinning the RSSI levels of STAs, then short beacons meant for oneparticular group of STAs (e.g., short beacons with TIM for this group ofSTAs only), may be encoded using a MCS that is robust for the RSSI binassociated with the group of STAs. This may be particularly useful ifthe STAs are immobile STAs such as sensors.

The STAs in the BSS may be grouped based on their STBC capabilities. AnAP may also divide the STAs into groups according to their STBCcapabilities. Short beacons meant for one particular group of STAs, forexample, short beacons with TIM for the group of STAs that are capableof STBC only, may be encoded using the lowest STBC MCS that may besupported by all the STAs in the group.

In accordance with the above described methods for beacon MCSadaptation, a result is reduction in system overhead caused by beacontransmission forced to use the lowest MCS supported in the BSS. Hence,WLAN systems including those based on new PHY and MAC extensionstargeted for smaller bandwidth transmissions (e.g., TGah), can benefit.

Short beacons may be used for support of increased range and coverage inWLAN systems, particularly those designed for sub-1 GHz operation.Specifically two methods are described below to extend the short beaconrange. A first method uses a lower and/or variable rate for transmissionof the short beacon, and a second method uses multiple antennatechniques, such as beamforming, and associated procedures, to extendthe transmission range. Both methods result in minimizing increasedsystem overhead. Each of these range extension methods may be employedin addition to, or in place of, other embodiments described herein forthe short beacon. In these methods, an Extended Range Short Beacon(ERSB) may be used for pre/non-associated STAs for network access, orfor associated STAs for broadcast of necessary information from AP, suchas the TIM element. Depending on the usage requirements, or use cases,different short beacon types may be used for different purposes. Asdescribed herein, there may be different short beacon types defined toaddress these purposes. The procedure(s) for use of these short beacontypes may be indicated by the primary, or legacy, beacon. For example aprimary beacon frame may contain information on the transmission timingof the short beacon.

In a first method for this embodiment, a short beacon with low data ratetransmission may have a MCS scheme with a low data rate, such as BPSKwith 1/2 coding rate for example. Such an MCS scheme with a repetition 2code would comply with IEEE 802.11ah networks for a 1 MHz bandwidthtransmission mode.

A low data rate transmission scheme may be used for the ERSB to supportan increased range. As a first example, repetition codes may be used,either in modulated symbol domain, or in coded bit domain, with orwithout interleaver between the repeated symbols/bits. In a secondexample for this method, the definition of very low rate codes, forexample, rate 1/4 codes, may be used on any one or more channel codingschemes including, convolutional codes, Low Density Parity Check (LDPC)codes or other channel codes, depending on the standard requirements. Ina third example of this method, use of space-time coding, such as STBCmay be used to extend the range. Each of these method examples mayrequire modifications to the PLCP header. Also the STF and LTF may needto be redesigned, or simply repeated.

In a second method for this embodiment, a short beacon with directionaltransmission may be used. A directional ERSB may be realized usingeither beamforming, or precoding. To enable either beamforming orprecoding, a set of antenna weights may be predefined by thespecification, preconfigured by the system, or set by an adaptivetraining procedure at the STA. According to the different ways forcomputing the weights, the resulting beacon may be a ‘precoded beacon’,‘sectorized beacon’ or ‘beamformed beacon’.

Due to the usage of the directional ERSB, different sets of weights maybe selected for different users. For example, for non-associated STAs,the AP may utilize a set of predefined weights, which may sectorize thespatial domain physically with carefully designed antenna patterns. Orthe AP may simply utilize a set of orthogonal weights and combination ofthe weights. For associated STAs with TIM expected to be received fromthe AP, or other multiple cast transmissions, the AP has the knowledgeabout the spatial signature of the STAs roughly. Thus, the AP may choosea group of users with similar spatial signature(s), then modulate thedirectional short beacon with that weight. The weight selection may bebased on a predefined code book, or a general beamforming technique.

In order to reduce the impact of hidden notes problem in the directionalbeacon transmission, two protection schemes may be utilized. The primarybeacon may broadcast the information when the next directional beaconwill be transmitted. Moreover, an extra Omni PLCP header may be addedbefore the directional short beacon PLCP Protocol Data Unit (PPDU) sothat other STAs may hear the Omni part of the directional beacon, andset NAV accordingly.

FIG. 15 shows an example of a directional ERSB transmitted with twodirections/weights. In this directional short beacon, one or moredirections/weights may be transmitted sequentially, shown as DirectionalPart 1 and Directional Part 2. As shown in FIG. 15, the Omni header partof the directional short beacon includes Omni STF (OSTF), Omni LTF(OLTF) and Omni SIG (OSIG) fields. In the Directional Parts 1 and 2, thesignal fields SIG1 and SIG2 may contain the same or differentinformation. Beacon fields Beacon1 and Beacon2 may contain the same ordifferent information according to the purpose of the directional ERSBand related short beacon strategies.

In accordance with the above described methods related to short beaconcoverage extension, a WLAN using short beacons may have increased rangeand coverage to support sub-1 GHz WiFi systems and Very High SpectrallyEfficient (VHSE) WLAN system requirements.

A new field of channel access parameters may be included in the shortbeacon and/or regular beacon. For example, channel access parameters mayinclude group ID(s) of STA group or groups that are allowed to accessthe upcoming beacon intervals and/or sub-intervals, (which may becontention-free or contention-based access).

A new field is included in the MLME-Scan.confirm primitive to reportpassive scan results obtained from short beacons as shown in Table 5.

TABLE 5 Name Type Valid Range Description BSSDescription Set of BSS N/AThe BSSDescription- FromShortBea- DescriptionFrom- FromShortBeaconSet isreturned conSet ShortBeacon to indicate the results of the scan requestderived from short beacons. It is a set containing zero or moreinstances of a BSSDescriptionFromShortBeacon.Each BSSDescriptionFromShortBeacon consists of the elements shown inTable 6.

TABLE 6 Name Type Valid Range Description Compressed Octet string 0-4octets The hashed SSID of the found BSS SSID Short Integer N/A The 4byte LSBs of the Timestamp of timestamp the received frame (proberesponse/beacon) from the found BSS Time to the next Integer N/A Thetime between the received short full beacon beacon frame to the nextfull beacon MAC Address MAC 6 bytes MAC Address of the AP is obtained ofthe AP address from the Source address (SA) in the received short beaconframe Access network As defined in IEEE 4 bits The type of accessnetwork (such as type (optional) Std 802.11 ™-2012: public, private andetc.) Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)Specifications IP address As defined in IEEE N/A Availability of IPaddress of various availability or Std 802.11u ™-2011 types of the foundBSS condensed IP address availability (optional) Channel As defined N/AParameters that indicate which Access herein STA(s) may conduct channelaccess Parameters in the upcoming beacon intervals and/or sub-intervals.A new sub-field to the BSSDescription field to report channel accessparameters obtained from the regular beacon may be added, as shown inTable 7.

TABLE 7 Valid Name Type Range Description Channel As defined N/AParameters that indicate which Access herein STA(s) may conduct channelParameters access in the upcoming beacon intervals and/or sub-intervals.

For the MLME-Scan.request, two new parameters called theMaxChannelTimeforShortBeacon and the MinChannelTimeforShortBeacon may beadded in MLME-Scan.request primitive to allow more efficient scanning,as shown in Table 8.

TABLE 8 Name Type Valid Range Description MaxChannelTime- Integer≤MaxChannel-Time The maximum time (in TU) to forShortBeacon spend oneach channel when scanning for short beacon, and is optionally presentif the dot11ah is true. MinChannelTime- Integer ≤MinChannel-Time Theminimum time (in TU) to forShortBeacon spend on each channel whenscanning for short beacon, and is optionally present if the dot11ah istrue.

To become a member of a particular ESS using passive scanning, a STA mayscan for beacon frames containing that ESS's SSID, and return all beaconframes matching the desired SSID in the BSSDescriptionSet parameter ofthe corresponding MLME-SCAN.confirm primitive with the appropriate bitsin the Capabilities Information field indicating whether the beaconframe came from an infrastructure BSS or IBSS.

A STA (e.g., an IEEE 802.11ah compliant STA) may additionally scan forshort beacon frames, returning all short beacon frames matching thedesired parameters, (such as SSID and etc.), in the correspondingMLME-SCAN.request primitive using BSSDescriptionFrom-ShortBeaconSet inthe MLME-SCAN.confirm primitive. For example, a Short Beacon frame canbe considered to be matched with the desired parameters in thecorresponding MLME-SCAN.request primitive when the compressed SSID ofreceived Short Beacon frames matches the hashed SSID or SSIDListparameter, (if they are specified in the corresponding MLME-SCAN.requestprimitive).

The STA may listen to each channel scanned for no longer than a maximumduration defined by the MaxChannelTime parameter. Alternatively, whenscanning for short beacons, a STA may listen to each channel scanned forno longer than a maximum duration defined by theMaxChannelTimeforShortBeacon, (as defined herein). In addition, whenscanning for short beacons, a STA may listen to each channel scanned forno less than a minimum duration defined by theMinChannelTimeforShortBeacon (as defined herein).

According to this embodiment, one MLME-Scan.request primitive of passivescan type may trigger two different scans: one for short beacon and theother for full beacon. The STA (e.g., a IEEE 802.11ah enabled STA), maythen perform passive scanning based on the following example procedure.

FIG. 16 shows a method flowchart for STA behavior of passive scanningusing short beacon in accordance with this embodiment. Upon receipt ofthe MLME-SCAN.request primitive with ScanType indicating passive scan, aSTA may perform passive scanning on each channel included in theChannelList parameter in the MLME-SCAN.request primitive.

The STA may scan the channel for short beacons first for the duration ofMaxChannelTimeforShortBeacon. Then, the STA may generate aMLME-SCAN.confirm primitive that contains the field ofBSSDescriptionFromShortBeaconSet to indicate the results obtained fromall the received short beacons.

The STA (via the SME within the STA) may evaluate the basic informationin the MLME-SCAN.confirm, (e.g., BSSDescriptionFromShortBeaconSet), orthe received short beacon to decide whether at least one found BSS isusable or worthy to read the corresponding full beacon. The decision canbe made based on one or any combination of several of the followingexample criteria.

If the MLME-SCAN.request primitive specifies a SSID or a SSID List, thenthe STA may compute the hash of the SSID or SSIDs in the SSID list andcompare with the received compressed SSID. If not matched for any foundBSS, the STA may decide not to read the corresponding full beacon.

If the MLME-SCAN.request primitive specifies a BSSID, then the STA maycompare the requested BSSID with the SA field of the received shortbeacon. If not matched for any found BSS, the STA may decide not to readthe corresponding full beacon.

If the MLME-SCAN.request primitive specifies a particular access networktype, then the STA may compare the access network type in theMLME-SCAN.request primitive with the network access type field in thereceived short beacon frame. If not matched for any found BSS, the STAmay decide not to read the corresponding full beacon.

If the IP address type that the STA supports is not available at anyfound BSS, (for example, IPv4 address not available and the STA is anIPV4 only STA), the STA may decide not to read the corresponding fullbeacon.

If the STA decides to read the corresponding full beacon, the STAselects one of the following methods. As a first method, the STA may goto doze/sleep mode and wakes up n time units (TUs) before the timeindicated by the field “Time to the next full beacon” to receive thefull beacon, where the value of n is a design parameter and may bespecified in the standards.

As a second method, the STA may take different actions depending on thewait time for the next full beacon. If time to the next full beaconminus n TUs is not greater than the MaxChannelTimeforShortBeacon, thenthe STA goes to doze/sleep mode and wakes up n TUs before the timeindicated by the field “Time to the next full beacon” to receive thefull beacon). If time to the next full beacon minus n TUs is larger thanthe MaxChannelTimefor-ShortBeacon, then the STA may scan for shortbeacons on the next channel(s) in the ChannelList, and tune back to thecurrent channel at least n TUs before the time indicated by the field“Time to the next full beacon” to receive the corresponding full Beacon.The scan results of the next channel(s) may be stored for the purpose ofa potential scan of full beacons on those channels later on. In thisway, total passive scanning time is reduced without more powerconsumption.

If the STA decides not to read the corresponding full beacon, then theSTA may scan the next channel according to the ChannelList parameter inthe MLME-SCAN.request primitive.

After scanning all the channels, the STA, (or the SME within the STA),may choose the AP(s) to associate to based on the information inreceived MLME-SCAN.confirm primitives.

The STA may receive some full beacons within the duration ofMaxChannelTimeforShortBeacon. In this case, the STA may proceedaccording to at least one of the following reporting options.

In a first option, the partial scan results of full beacons may bereported using the BSSDescriptionSet with a newly-defined ResultCode of“Incomplete” within the same MLME-SCAN.confirm that reports the scanresults of short beacons. For each AP/BSS whose full beacon informationis reported in the MLME-SCAN.confirm, the STA may choose not to reportits short beacon information. For each AP/BSS whose full beaconinformation is already reported in the MLME-SCAN.confirm, the STA maynot read the corresponding full beacon again in as in steps 1609, 1610.

In second option, the partial scan results of full beacons are notreported in the MLME-SCAN.confirm.

In order to support the stopping of processing a packet that iscurrently being received, a Physical Layer Convergence Procedure (PLCP)receive procedure is modified and new primitives may be defined. FIG. 17shows an example of a modified PLCP receive procedure with newly definedprimitives to support the stopping of processing of packets. The PLCPreceive procedure is generically described and may be applied to anyWiFi and wireless standards. The SIG field and the training fieldsdepicted in FIG. 17 may have multiple parts and may be located in anyorder in any part of the frame. The newly defined primitives shown inFIG. 17 are PHY-RXSTOP.request 1701, PHY-RXSTOP.confirm 1702,PMD_RXSTOP.request 1703, PMD_RXSTOP.confirm 1704.

The PHY-RXSTOP.request 1701 primitive is a request by the MAC sublayerto the local PHY entity to stop processing a PPDU that the PHY entity iscurrently receiving. This primitive has no parameters and may be issuedby the MAC sublayer to the PHY entity when the MAC sublayer detects thatthe packet that is currently being received is not needed by the MACsublayer. This primitive may be issued at any time between the time whenthe local PHY layer issued a PHY-RXSTART.indication primitive to the MACsublayer and the time when the local PHY layer issued aPHY-RXEND.indication primitive to the MAC sublayer for the same PPDU.The effect of receipt of this primitive by the PHY entity may be to stopthe local receive state machine, including issuing a PMD_RXSTOP.request1703 to the PMD sublayer.

The PHY-RXSTOP.confirm 1702 primitive may be issued by the PHY to thelocal MAC entity to confirm the stop of processing of a PPDU that waspreviously being processed. The PHY issues this primitive in response toevery PHY-RXSTOP.request 1701 primitive issued by the MAC sublayer. ThePHY-RXSTOP.request(PacketEndTime) primitive may contain no parameters.Alternatively, it may have a parameter PacketEndTime. PacketEndTime mayindicate the end of the PPDU that was previously being received butwhose processing was stopped by the PHY-RXSTOP.request 1701 primitive bythe local MAC sublayer. In another example, PacketEndTime may indicatethe end of the TXOP indicated by for example, length field or the ACKfields, in the PLCP header. This primitive may be issued by the PHY tothe MAC entity in response to at least one of the followingconditions: 1) the PHY has received a PHY-RXSTOP.request 1701 primitivefrom the MAC entity; 2) the PLCP has issued PMD_RXSTOP.request 1703primitive; or 3) the PMD has issued PMD-RXSTOP.confirm 1704 primitive tothe PLCP. The effect of receipt of this primitive by the MAC sublayermay be to enter Doze State for a period. Such a period may last untilthe end of the current PPDU, until the end of the current TXOP, untilthe PHY entity issues to the MAC sublayer PHY-CCA.indication(IDLE) or ofany other length. The MAC sublayer may enter CS/CCA state after such aperiod.

The PMD_RXSTOP.request 1703 primitive, generated by the PHY PLCPsublayer, may initiate PPDU transmission by the Physical MediumDependent (PMD) layer. This primitive may have no parameters and may begenerated by the PLCP sublayer to terminate the PMD layer reception ofthe PPDU. The PHY-RXSTOP.request 1701 primitive may be provided to thePLCP sublayer prior to issuing the PMD_RXSTOP.request 1703 command. Theprimitive PMD_RXSTOP.request 1703 terminates the reception of a PPDU bythe PMD sublayer.

The PMD_RXSTOP.confirm 1704 primitive, generated by the PMD entity, mayindicate the end of PPDU reception by the PMD layer. This primitive mayhave no parameters and may be generated by the PMD entity when the PMDentity has received a PMD_RXSTOP.request 1703 from the PHY PLCP sublayerand the PMD entity has stopped the reception of the PPDU that it waspreviously receiving. The PLCP sublayer may determine that the receptionof the PPDU is stopped at the PMD sublayer. The PLCP sublayer may issuea PHY-RXSTOP.confirm 1702 to the MAC sublayer to confirm the stop of thereception of the PPDU.

The existing primitive PHY-RXEND.indication may be modified by adding avalue to its parameter RXERROR. A value of “RXSTOPPED” may be added as avalid value for RXERROR indicating that the reception of a PPDU has beenstopped by explicit commands.

As shown in FIG. 17, any time between the time when a PLCP sublayerissues a PHY-RXSTART.indication primitive to the MAC sublayer and thetime when the PLCP sublayer issues a PHY-RXEND.indication primitive tothe MAC sublayer, the MAC sublayer may determine that a packet that iscurrently being received is not needed. For example, this may happenwhen the MAC sublayer discovers that a beacon frame is being receivedand it does not need any IEs or it has received all the IEs that itneeds. This may potentially occur after having verified the integrity ofthe received MPDU using mid-CRC or other methods. In another example,the MAC sublayer has decoded the MAC header and discovered that the MPDUis not meant for itself. This may potentially occur after havingverified the integrity of the received MPDU using a specially designedFCS for the MAC header or other methods.

The MAC sublayer may issue a PHY-RXSTOP.request 1701 primitive to thelocal PHY entity to request that the local PHY entity should stopprocessing the PPDU that is currently being received.

The PHY PLCP sublayer may then stop decoding and descrambling the codedPSDU, and issue a PMD_RXSTOP.request 1703 primitive to the PMD sublayer.

The PMD sublayer may then stop receiving the PPDU and issue aPMD_RXSTOP.confirm 1704 to confirm that the PMD sublayer has stoppedprocessing the PPDU.

The PHY PLCP sublayer may then issue a PHY-RXSTOP.confirm 1702 to theMAC sublayer to confirm that the PHY entity has stopped processing thePPDU. The MAC sublayer may then enter the Doze state for a period. Thisperiod may last until the end of the current PPDU, the end of thecurrent TXOP, until the PHY entity issues to the MAC sublayerPHY-CCA.indication(IDLE) or of any other length. The MAC sublayer mayenter Carrier Sense/Clear Channel Assessment (CS/CCA) state after such aperiod. The MAC sublayer may also issue a primitive to wake up the localPHY entity after such a period.

The local PHY entity may issue a PHY-RXEND.indication at the scheduledend of the PPDU whose processing has been stopped or at the end of theTXOP to provide timing to the MAC sublayer. The PHY-RXEND.indication mayhave the parameter of RXERROR set to a new value “RXSTOPPED”.

The local PHY entity may start to monitor the wireless medium at thescheduled end of the PPDU whose processing has been stopped or at theend of the TXOP and issue a PHY-CCA.indication (IDLE) to the MACsublayer.

In another example, the local PHY entity may detect from the PLCPheaders that a PPDU that is currently being received is not needed, byfor example, examining the partial association identifier (AID) field,or any existing or new fields such as a Direction Indication field,length field, and the like. The PHY entity may also stop processing ofthe PPDU using the procedure described herein without receiving commandsfrom the MAC sublayer.

Any time between the time when the PMD sublayer issues aPMD_data.indication(first) primitive to the PLCP sublayer and the timewhen the PMD sublayer issues the last PMD_data.indication primitive tothe PLCP sublayer, the PLCP sublayer may determine that a packet that iscurrently being received is not needed. For example, when the PartialAID or Group ID does not match those of the current STA. In anotherexample, the PLCP sublayer detects that the Direction Indication Bitindicates that the packet is sent to the AP while the current STA is anon-AP STA.

The PHY PLCP sublayer may then stop decoding and descrambling the codedPSDU, and issues a PMD_RXSTOP.request 1703 primitive to the PMDsublayer. The PMD sublayer may then stop receiving the PPDU and issues aPMD_RXSTOP.confirm 1704 message to confirm that the PMD sublayer hasstopped processing the PPDU.

The PHY entity may issue a PHY-RXEND.indication at the scheduled end ofthe PPDU whose processing has been stopped or at the end of the TXOP orany other time to provide timing to the MAC sublayer. ThePHY-RXEND.indication may have the parameter of RXERROR set to a newvalue “RXSTOPPED”.

The local PHY entity may start to monitor the wireless medium at thescheduled end of the PPDU whose processing has been stopped or at theend of the TXOP or any other time and issue a PHY-CCA.indication(IDLE)to the MAC sublayer.

In accordance with the above methods relating to stopping packetprocessing, a STA that is interested in no IEs or just a few IEs isenabled to stop processing of a long beacon. The STA may desire to stopprocessing a packet after recognizing certain aspects of the packetsthat are currently being received that do not fit its needs. Forexample, this may be the case when a STA recognizes from the preamblethat it cannot be possibly be the destination of the packet that isbeing received.

Although the solutions described herein consider IEEE 802.11 specificprotocols, it is understood that the solutions described herein are notrestricted to this scenario and are applicable to other wireless systemsas well.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element may be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A method implemented by a station (STA) inwireless communication with a wireless local area network, the methodcomprising: receiving a short beacon comprising a element that indicatesa version of the short beacon; on a condition that the element indicatesthat the short beacon has not changed from a known version of the shortbeacon, accessing a medium; and on a condition that the elementindicates that the short beacon has changed from a known version of theshort beacon, performing at least one of decoding the short beacon orsending a probe request, and accessing the medium.
 2. The method ofclaim 1, the element comprising a version number information field. 3.The method of claim 1, wherein the short beacon includes fast initiallink setup (FILS) information, the method further comprising: comparinginformation of a MLME-SCAN.request primitive with the FILS information;invoking a MLME-SCAN.confirm primitive in response to scan results;reporting the MLME-SCAN.confirm primitive on a condition that thecomparing information produced a match; and selecting an access pointAP, for linking on a condition that the STA determines that sufficientnetwork service information was obtained from the scan and that the APsatisfies STA requirements.
 4. The method of claim 2, wherein theversion number information field comprises at least one of a CommonAdvertisement Group (CAG) number or an AP Configuration Sequence Number(AP-CSN).
 5. A method implemented in an access point (AP) of a wirelesslocal area network (WLAN), the method comprising: determining an elementvalue based on whether a beacon has changed; and sending the beaconcomprising the element value to a station (STA), the element enablingthe STA to determine whether to perform at least one of the following:decoding the beacon, or sending a probe request.
 6. The method of claim5, the element value comprising a version number information field. 7.The method of claim 5, further comprising: broadcasting a link setupbeacon having a transmission periodicity defined according to systemconfiguration parameters and used to allow the STA to detect the WLAN.8. The method of claim 5, further comprising: sending a link andoperation maintenance beacon as a unicast, broadcast or multicasttransmission having a transmission periodicity defined according tosystem configuration parameters and used to alert another STA to linkoperation changes.
 9. The method of claim 5, further comprising: sendingan operation initialization beacon as a unicast, broadcast or multicasttransmission aperiodically, wherein the sending is triggered by an eventin response to a received indication from another STA for attemptedconnection establishment.
 10. The method of claim 5, further comprising:sending a traffic information beacon as a unicast, broadcast ormulticast transmission either periodically or aperiodically, wherein thesending is triggered by an event, wherein listening window informationassociated with the traffic indication beacon is provided to the STAwhile the STA is in a power saving mode.
 11. The method of claim 6,wherein the version number information field comprises at least one of aCommon Advertisement Group (CAG) number or an AP Configuration SequenceNumber (AP-CSN).
 12. The method of claim 5, further comprising: defininga plurality of beacons according to a multiple level beacon scheme inwhich each beacon level has a different transmission periodicityaccording to system configuration parameters, wherein content in eachdefined multiple level beacon is at least one of having partial overlap,having no overlap, or being forward inclusive.
 13. A station (STA)comprising a processor configured to: receive a short beacon comprisingan element that indicates a version of the short beacon; on a conditionthat the element indicates that the short beacon has not changed from aknown version of the short beacon, access a medium; and on a conditionthat the element indicates that the short beacon has changed from aknown version of the short beacon, perform at least one of decoding theshort beacon or sending a probe request, and access the medium.
 14. TheSTA of claim 13, the element comprising a version number informationfield.
 15. The STA of claim 13, wherein the short beacon includes fastinitial link setup (FILS) information, the processor further configuredto: compare information of a MLME-SCAN.request primitive with the FILSinformation; invoke a MLME-SCAN.confirm primitive in response to scanresults; report the MLME-SCAN.confirm primitive on a condition that thecomparing information produced a match; and select an access point AP,for linking on a condition that the STA determines that sufficientnetwork service information was obtained from the scan and that the APsatisfies STA requirements.
 16. The STA of claim 14, wherein the versionnumber information field comprises at least one of a CommonAdvertisement Group (CAG) number or an AP Configuration Sequence Number(AP-CSN).
 17. A station (STA) implemented as an access point (AP) of awireless local area network (WLAN), the STA comprising a processorconfigured to: determine an element value based on whether a beacon haschanged; and send the beacon comprising the element value to a targetstation (STA), the element enabling the target STA to determine whetherto perform at least one of the following: decoding the beacon, orsending a probe request.
 18. The STA implemented as an AP of claim 17,the element value comprising a version number information field value.19. The STA implemented as an AP of claim 18, wherein the version numberinformation field comprises at least one of a Common Advertisement Group(CAG) number or an AP Configuration Sequence Number (AP-CSN).
 20. TheSTA implemented as an AP of claim 17, the processor further configuredto: define a plurality of beacons according to a multiple level beaconscheme in which each beacon level has a different transmissionperiodicity according to system configuration parameters, whereincontent in each defined multiple level beacon is at least one of havingpartial overlap, having no overlap, or being forward inclusive.